pyrimidine-Based Potent and Selective CCK

J. Med. Chem. 1999, 42, 4659-4668

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5-(Tryptophyl)amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine-Based Potent and Selective CCK1 Receptor Antagonists: Structural Modifications at the Tryptophan Domain Jose´ M. Bartolome´-Nebreda,§ Isabel Go´mez-Monterrey,§ M. Teresa Garcıá-Lo´pez,§ Rosario Gonza´lez-Mun˜iz,§ Mercedes Martıń-Martıńez,§ Santiago Ballaz,‡ Edurne Cenarruzabeitia,‡ Miriam LaTorre,‡ Joaquıń Del Rıó,‡ and Rosario Herranz*,§ Insituto de Quı´mica Me´ dica (CSIC), Juan de la Cierva 3, E-28006 Madrd, Spain, and Departamento de Farmacologıá, Universidad de Navarra, Irunlarrea 1, E-31080 Pamplona, Spain Received May 10, 1999

Analogues of the previously reported potent and highly selective CCK1 receptor antagonist (4aS,5R)-2-benzyl-5-(N-Boc-tryptophyl)amino-1,3-dioxoperhydropyrido-[1,2-c]pyrimidine (2a) were prepared to explore the structural requirements at the Boc-tryptophan domain for CCK1 receptor affinity. Structural modifications of 2a involved the Trp side chain, its conformational freedom, the Boc group, and the carboxamide bond. Results of the CCK binding and in vitro functional activity evaluation showed three highly strict structural requirements: the type and orientation of the Trp side chain, the H-bonding acceptor carbonyl group of the carboxamide bond, and the presence of the Trp amino protection Boc. Replacement of this acid-labile group with 3,3-dimethylbutyryl or tert-butylaminocarbonyl conferred acid stability to analogues 14a and 15a, which retained a high potency and selectivity in binding to CCK1 receptors, as well as an in vivo antagonist activity against the acute pancreatitis induced by caerulein in rats. Oral administration of compounds 14a and 15a also produced a lasting antagonism to the hypomotility induced by CCK-8 in mice, suggesting a good bioavailability and metabolic stability. Introduction The peptide Cholecystokinin (CCK) displays hormonal and neurotransmitter activities in the digestive tract and in the central nervous system (CNS)1 and exerts its biological effects via at least two G protein coupled receptor subtypes, termed CCK1 and CCK2.2 CCK1 receptors are mainly found in the digestive tract, where they are involved in the diverse effects of CCK on the regulation of digestive processes1 (pancreatic enzyme secretion, gut motility, and gallbladder contraction). They are also found in selected CNS areas, where they regulate dopamine release1-3 and antagonize opioid analgesia.1,4 Furthermore, CCK1 receptors mediate the satiety effect of CCK in the CNS and in the peripheral nervous system1,2,5 and are present in several tumoral cell lines.2 CCK2 receptors are predominantly found throughout the CNS2 and are considered to be primarily involved in anxiety-related conditions,6-9 memory processes,1,10 and also in neuropsychiatric disorders.1,11,12 The variety of possible therapeutic utilities for CCK receptor agonists and antagonists has prompted an intensive research in this area and, over the past decade, a number of potent and selective non-peptide CCK1 and CCK2 receptor antagonists have been reported.13 Some of these antagonists have been useful tools for characterizing the two CCK receptor subtypes and for gaining further insight into the functional significance of CCK in the periphery and in the CNS; nevertheless, the physiological effects of CCK mediated § ‡

Instituto de Quı´mica Me´dica. Departamento de Farmacologıá.

by CCK1 or CCK2 receptors are not completely established.1,2 Despite the predominant role suggested for CCK2 receptors in anxiety and in the control of nociception, anxiolytic-like effects and enhancement of morphine analgesia have been reported for the typical CCK1 antagonist Devazepide14,15 (1). It has been suggested16 that these effects could be due to the blockade of CCK2 receptors by Devazepide at high doses, since this

compound is not completely devoid of affinity for this receptor subtype (selectivity for CCK1 over CCK2 varies from 170-17 to 3000-fold18). Caution has also been recommended, in general, when attempting to differentiate between effects mediated by CCK1 or CCK2 receptors with Devazepide.19 In view of these facts, the development of CCK receptor antagonists with higher selectivity for CCK1 over CCK2 receptors is of interest in order to shed further light on the functional roles of CCK receptor subtypes. In this regard, we recently reported the design, synthesis20 and pharmacological properties21 of the 5-(tryptophyl)amino-1,3-dioxoperhydropyrido-[1,2-c]pyrimidine derivative 2a (IQM-95,333), a highly potent and selective CCK1 receptor antagonist,

10.1021/jm991078x CCC: $18.00 © 1999 American Chemical Society Published on Web 10/07/1999

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Journal of Medicinal Chemistry, 1999, Vol. 42, No. 22

both in vitro and in vivo. This novel compound showed a CCK1 receptor affinity similar to that of Devazepide,20 but it was virtually devoid of affinity at brain CCK2 receptors. Interestingly, compound 2a also showed a marked anxiolytic-like activity in animal models, and blocked the CCK-8-induced hypophagia and hypolocomotion effects after intraperitoneal administration.21 From the first modifications performed on compound 2a, the 4a,5-trans stereochemistry of the 1,3-dioxoperhydropyrido[1,2-c]pyrimidine skeleton and the L-configuration of the Boc-Trp residue emerged as essential features for CCK1 binding affinity and subtype receptor selectivity.20 Modifications of this residue have been now performed in order to define which functional groups are critical for binding to the receptor and to explore the tolerance of the receptor to conformational constraints. These modifications involve the Trp side chain, its conformational freedom, the Boc group and the carboxamide bond. Additionally, some of the modifications herein reported could lead to analogues with enhanced oral bioavailability and duration of action. The present paper deals with the synthesis, CCK receptor binding profile, and in vivo antagonist activity against the acute pancreatitis induced by caerulein in rats and against the hypomotility induced by CCK-8 in mice of this series of Boc-Trp modified analogues of the above indicated CCK1 receptor antagonists.

Bartolome´ -Nebreda et al.

Scheme 1a

Chemistry In an attempt to reduce the molecular weight of the parent compounds 2, we initially synthesized analogues 7 and 8, in which the Boc-Trp moiety was respectively replaced by indol-2-yl-carbonyl, the key group in Devazepide for binding to CCK1 receptors,22 and the indol-3-yl-acetyl residue.23 Then, analogues 9-12, containing Phe, R-Me-L-Trp, R-Me-D-Trp, and the tetrahydro-β-carbolin-3-yl-carbonyl in place of Trp, were prepared in order to study the influence of the type and conformational freedom of the side chain upon the binding affinity at CCK receptors. Compounds 7-12 were prepared following a synthetic route similar to that used for the synthesis of the model compounds 2, as indicated in Scheme 1. This route involves sequential N-Boc removal in the 5-Boc-amino-1,3-dioxoperhydropyrido-[1,2-c]pyrimidine derivatives 6, followed by coupling with the corresponding acid or Boc protected amino acid derivative. The starting 1,3-dioxoperhydropyrido[1,2-c]pyrimidines 6 were obtained in four steps from Boc-D-Orn(Z)-OH, as a (4:1) racemic mixture of the (4aS,5R)- and (4aR,5S)-isomers, or as a (1:4) mixture from Boc-L-Orn(Z)-OH, as previously described.20 Therefore, compounds 7 and 8 were obtained as racemic mixtures, and 9-12 were obtained as diastereoisomeric mixtures a,b, which could be chromatographically resolved only in the cases of 9 and 12. The 1H NMR data for the lead compound 2a, particularly the Trp JR,β values (2.7 and 5.2 Hz) and the NOE effect between the NH-Boc and the indole 2-H protons, suggested a preferred gauche (-) conformation for the Trp side chain (χ1 ≈ -60)24,25 (Figure 1). We expected that the tetrahydro-β-carboline skeleton in compound 12a could fix the Trp preferred conformation. However, the J3,4 values in the 1H NMR spectrum of 12a (0 and 6 Hz) indicated an equatorial disposition for the tetra-

a Reagents: (a) 1,1′-carbonyldiimidazole, LiCH CO Et, THF; (b) 2 2 H2, Pd(C), EtOH or MeOH; (c) benzyl isocyanate, THF; (d) NaH, THF; (e) TFA, CH2Cl2; (f) R-OH, BOP, Et3N.

Figure 1. Newman projections of the g(-) and g(+) staggered ratational states of the CR-Cβ bond in the Trp residue of compound 2a, and the corresponding conformations of the tetrahydro-β-carboline skeleton in 12a.

hydro-β-carboline 3-H proton and, therefore, a fixed gauche (+) conformation (χ1 ≈ 60) for the restricted Trp side chain in this compound. Taking into account the expected low stability of the N-Boc protection in the acid medium of the stomach,26 our second objective was to change this protection in

Selective CCK1 Receptor Antagonists

Journal of Medicinal Chemistry, 1999, Vol. 42, No. 22 4661

Scheme 2a

Scheme 3a

a Reagents: (a) TFA, CH Cl ; (b) 3,3-dimethylbutyryl chloride, 2 2 Et3N, THF; (c) t-butyl isocyanate, Et3N,THF; (d) 1-adamantylcarbonyl chloride, Et3N, THF; (e) 2-adamantyl chloroformate, Et3N, THF.

order to increase the stability in acid pH, without loss in the binding affinity. With this aim, the urethane Boc group was replaced in 2a by its carboxamide and ureido bioisosters, the 3,3-dimethylbutyryl and tert-butylaminocarbonyl groups, respectively, giving compounds 14a and 15a, and in 2b by the N protecting groups used in the series of dipeptoid CCK receptor antagonists,27 1-adamantylcarbonyl (1-Adc) and 2-adamantyloxycarbonyl (2-Adoc), obtaining analogues 16b and 17b (Scheme 2). A comparative RP HPLC study on the stability of compounds 2a, 14a and 15a in acid medium showed that the half-life of 2a in 2 N HCl solution in (1:1) H2OMeOH was 17 min, while that of 15a was 11 days, and the analogue 14a remained unaltered after that time. Finally, the carboxamide bond between the Trp and the 1,3-dioxoperhydropyrido-[1,2-c]pyrimidine skeleton of compound 2a was replaced by the reduced peptide bond Ψ[CH2NH] in compounds 18a,b and by the cyanomethyleneamino Ψ[CH(CN)NH] peptide bond surrogate in analogues 19-22 (Scheme 3). Both peptide bond modifications have been used in pseudopeptides to increase stability toward peptidases and to study if the replaced peptide bond has a functional role or merely serves to orient and align the side chains.28-30 The Ψ[CH2NH] peptide bond surrogate causes an increase of flexibility in the peptide backbone and a decrease in the H-bonding properties by loss of the H-bonding acceptor amide carbonyl group.28,31 In contrast, the Ψ[CH(CN)NH] was proposed as peptide bond surrogate based on the hypothesis that its cyano group keeps H-bonding acceptor properties and that it could impart higher backbone rigidity than the Ψ[CH2NH].32,33 On the other hand, both peptide bond surrogates have the additional advantage of introducing a basic NH, which could be protonated, enhancing the solubility in aqueous systems.28 The reduced peptide bond analogues 18a,b were obtained from the (4:1) racemic mixture of the 1,3dioxoperhydropyrido[1,2-c]pyrimidine derivatives 6a,b by N-Boc removal, followed by N-alkylation of the resulting deprotected compounds with Boc-L-trypto-

a Reagents: (a) TFA, CH Cl ; (b) Boc-L-Trp-H, Et N, ZnCl , 2 2 3 2 NaBH3CN, MeOH; (c) Boc-L-Trp-H or Z-L-Trp-H, ZnCl2, TMSCN, MeOH; (d) H2, Pd(C), (Boc)2O, MeOH; (e) H2, Pd(C), MeOH; (f) bis(trichloromethyl)carbonate, Et3N, CH2Cl2.

phanal, using NaBH3CN as reducing agent in the presence of ZnCl2. Only the major isomer 18a could be isolated from the diastereoisomeric mixture 18a,b. With respect to the cyanomethyleneamino analogues 19-22, these were prepared applying our methodology,34 which involves reaction of the 1,3-dioxoperhydropyrido[1,2-c]pyrimidine derivatives 6a,b, after N-Boc deprotection, with Boc-L-tryptophanal or Z-L-tryptophanal and (trimethylsilyl)cyanide (TMSCN) in the presence of ZnCl2. In this process a new chiral center is generated; therefore, in the reaction with Boc-L-tryptophanal from the (4:1) racemic mixture 6a,b, two isomers with a (4aS,5R)-configuration [19a (31%) and 20a (21%)] were obtained, and only one (19b (9%)) with the (4aR,5S)configuration was obtained. The assignment of the absolute configuration of the new generated stereogenic center is usually made through the formation of an imidazolidin-2-one ring.34 For this purpose it was necessary to remove the Trp amino-protection. However, the Boc removal was not possible in compounds 19 and 20 due to the extreme susceptibility of the indole ring of these compounds to oxidative degradation in acid media,

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Table 1. Inhibition of the [3H]pCCK-8 Specific Binding to Rat Pancreas (CCK1) and Cerebral Cortex Membranes (CCK2) by Compounds 7-12

IC50 (nM)a compd CCK-8 Devazepide 2a 2b 7ab 8ab 9a 10ab 11ab 12a 12b b

stereochemistry

(4aS,5R) (4aR,5S) (4:1) (4aR,5S):(4aS,5R) (4:1) (4aR,5S):(4aS,5R) (4aS,5R) (6:1) (4aS,5R):(4aR,5S) (6:1) (4aS,5R):(4aR,5S) (4aS,5R) (4aR,5S)

R

CCK1

CCK2

Boc-L-Trp Boc-L-Trp In-2-yl-CO In-3-yl-CH2-CO Boc-L-Phe Boc-R-Me-L-Trp Boc-R-Me-D-Trp 2-Boc-THBC-3-yl-COb 2-Boc-THBC-3-yl-COb

1.04 ( 0.08 0.71 ( 0.05 1.59 ( 0.10 22.7 ( 4.0 >1000 >1000 65.7 ( 22.6 42.4 1236 226 >1000

5.60 ( 0.30 696 ( 134 >10000 6153 >10000 >10000 >10000 >10000 >10000 >10000 >10000

a Values are the mean or mean ( SEM of at least three experiments, performed with seven concentrations of test compounds in triplicate. THBC ) tetrahydro-β-carboline.

Table 2. Inhibition of the [3H]pCCK-8 Specific Binding to Rat Pancreas (CCK1) and Cerebral Cortex Membranes (CCK2) by Compounds 13-22

IC50 (nM)a compd Devazepide 2a 2b 13ab 13bb 14a 15a 16b 17b 18a 19a 20a 21a 22a b

stereochemistry (4aS,5R) (4aR,5S) (4aS,5R) (4aR,5S) (4aS,5R) (4aS,5R) (4aR,5S) (4aR,5S) (4aS,5R) (4aS,5R) (4aS,5R) (4aS,5R) (4aS,5R)

R1

X

CCK1

CCK2

Boc Boc H H tBut-CH -CO 2 tBut-HN-CO 1-Adc 2-Adoc Boc Boc Boc Z Z

CO CO CO CO CO CO CO CO CH2 [(R)CHCN] [(S)CHCN] [(R)CHCN] [(S)CHCN]

0.71 ( 0.05 1.59 ( 0.10 22.7 ( 4.0 >1000 >1000 4.43 ( 0.36 0.91 ( 0.08 486 340 >1000 7.69 ( 0.86 32.6 ( 5.26 >1000 >1000

696 ( 134 >10000 6153 >10000 >10000 >10000 >10000 4390 3430 >10000 >10000 >10000 >10000 >10000

a Values are the mean or mean ( SEM of at least three experiments, performed with seven concentrations of test compounds in triplicate. Tested as trifluoroacetate salt.

even by using different described conditions to minimize this problem.35 In view of the difficulties in removing the Boc protection, the Z protected analogues 21a (34%), 22a (17%), and 21b (10%) were prepared similarly. Then, after Z removal in 21a and 22a by catalytic hydrogenolysis, both of the resulting deprotected diastereoisomers 23a and 24a were subjected to reaction with bis(trichloromethyl)carbonate. However, only the isomer 23a led to the corresponding imidazolidin-2-one derivative 25a. The absolute configuration at the C5 of the imidazolidin-2-one ring of this compound, and therefore at the Ψ[CH(CN)NH] chiral center of 21a and 23a, was established on the basis of its J4,5 value (5 Hz) in its 1H NMR spectrum, indicative of a trans disposition for the 4-H and 5-H imidazolidin-2-one protons.34 Afterward, the configurational assignment in the Boc ana-

logues was made through the catalytic hydrogenolysis of 21a in the presence of di(tert-butyl) dicarbonate, which led directly to the major diastereoisomer 19a. The low amount obtained of the minor isomers 19b and 21b did not allow their configuration assignment. Biological Results and Discussion The affinity of the new 1,3-dioxoperhydropyrido[1,2c]pyrimidine derivatives 7-22 at CCK1 and CCK2 receptors was determined by measuring the displacement of [3H]propionyl-CCK-8 binding to rat pancreatic and cerebral cortex homogenates, respectively, as previously described.36 The data are depicted in Tables 1 and 2. For comparative purposes CCK-8, Devazepide, and the model compounds 2a and 2b were also included in the assay. Like these model compounds, the new 1,3-


dioxoperhydropyrido[1,2-c]pyrimidine derivatives 7-22 bound preferentially to the CCK1 receptor subtype. The replacement of Boc-Trp by the key Devazepide pharmacophoric group indol-2-yl-carbonyl and by its analogue indol-3-yl-acetyl in compounds 7 and 8, respectively, led to the complete loss of affinity (Table 1). The phenylalanine analogue 9a showed 1 order of magnitude lower CCK1 binding potency than the lead compound 2a. In contrast to the good results obtained in the dipeptoid CCK antagonist series by introducing an R-methyl substitution into their Trp residue,27,37,38 the introduction of this substitution into 2a or in its D-Trp analogue20 to give 10 and 11 led to a decrease of 1 and 3 orders of magnitude, respectively, in the binding affinity. The conformational restriction introduced by the tetrahydro-β-carboline system into 12a had a strong detrimental effect on the binding affinity. This effect could be due to the aforementioned fact that this skeleton fixes the gauche (+) Trp side chain conformation and not the preferred gauche (-) conformation of the prototype 2a. In regard to the Trp amino protection (Table 2), it seems necessary for binding to CCK1 receptors, as indicated by the inactivation of compounds 2a and 2b when deprotected to give 13a and 13b. The replacement of the urethane N-Boc protection of 2a by its bioisosters, more stable to chemical degradation in acid media, the 3,3-dimethylbutyryl and tert-butylaminocarbonyl groups in 14a and 15a did not have a significant effect upon their affinity at CCK receptors. However, the exchange of this protection in 2b for the usual27 protections in dipeptoid antagonist 1-adamantylcarbonyl or 2-adamantyloxycarbonyl led to 1 order of magnitude lower CCK1 binding potency in analogues 16b and 17b. This decrease, along with the fact that this replacement was the only modification which produced a slight increase in CCK2 binding affinity, discouraged the preparation of the corresponding diastereoisomers 16a and 17a. Finally, in relation to the carboxamide bond (Table 2), its replacement by the reduced peptide bond in compound 18a led to the complete loss of activity, while the incorporation of the [CH(CN)NH] group as a carboxamide surrogate was translated into a small decrease in the binding affinity for the (R)-epimer 19a and into 1 order of magnitude lower potency in the case of the (S)-epimer 20a. As the main difference between the [CH2NH] and the [CH(CN)NH] carboxamide surrogates lies in their H-bonding properties, rather than in their geometry,31 these data indicate the importance of the H-bonding acceptor amide carbonyl or cyano groups for the binding of 2a or 19a to CCK1 receptors. It also confirms the utility of the [CH(CN)NH] group as a carboxamide surrogate.31 It is also interesting to note the complete loss of affinity when the Boc protection of 19a and 20a was exchanged for the Z protection in 21a and 22a. Compounds with the higher affinity at CCK1 receptors, 14a and 15a, were tested in vivo for their protective effect on the experimental acute pancreatitis induced by caerulein in rats, which is known to be sensitive to CCK1 antagonists,39 and for their antagonism to the hypomotility induced by CCK-8 in mice, which is also selectively reversed by antagonists at this CCK receptor subtype.40 The model compound 2a, as well as Devazepide, were comparatively included in these studies.

Journal of Medicinal Chemistry, 1999, Vol. 42, No. 22 4663 Table 3. Effect of Intraperitoneal Administration of CCK1 Antagonists on the Increase in Plasma Amylase and Lipase Activities Induced by Caerulein in Ratsa treatment

plasma amylase (IU/mL)

plasma lipase (IU/mL)

vehicle caerulein Devazepide (0.1) + caerulein Devazepide (1) + caerulein 2a (0.1) + caerulein 2a (1) + caerulein 14a (0.1) + caerulein 14a (1) + caerulein 15a (0.1) + caerulein 15a (1) + caerulein

2073 ( 108 52101 ( 2221 8793 ( 1353 3650 ( 352** 35985 ( 6387 2721 ( 275** 61102 ( 3466 28015 ( 4774** 27103 ( 3539** 5326 ( 434**

15 ( 1 3100 ( 146 125 ( 26** 26 ( 2** 1943 ( 505* 112 ( 21** 2956 ( 212 1140 ( 218** 1667 ( 224** 36 ( 5**

a Pancreatitis induced by four sc injections of caerulein (10 µg/ kg) at hourly intervals. Test compounds (doses in mg/kg ip) given 30 min before the first caerulein injection *p < 0.05, **p < 0.01 vs caerulein (ANOVA followed by Sheffe´’s test).

Table 4. Effect of Oral Administration of CCK1 Antagonists on the Increase in Plasma Amylase and Lipase Activities Induced by Caerulein in Ratsa treatment

plasma amylase (IU/mL)

plasma lipase (IU/mL)

vehicle caerulein Devazepide (0.1) + caerulein Devazepide (1) + caerulein 2a (0.1) + caerulein 2a (1) + caerulein 14a (0.1) + caerulein 14a (1) + caerulein 15a (0.1) + caerulein 15a (1) + caerulein

3308 ( 285 39293 ( 3522 7733 ( 1209** 4578 ( 516** 37753 ( 1682 31205 ( 1900 51420 ( 3673 46591 ( 2292 28939 ( 2330 19967 ( 552**

15 ( 1 2801 ( 288 871 ( 351** 57 ( 9** 2837 ( 184 1948 ( 232 3089 ( 128 3375 ( 73 2200 ( 164 1062 ( 122**

a Pancreatitis induced like in Table 3. Test compounds (doses in mg/kg po) given 60 min before the first caerulein injection *p < 0.05, **p < 0.01 vs caerulein (ANOVA followed by Sheffe´’s test).

All of the tested compounds, at the same dose of 1 mg/kg ip, were able to significantly prevent in the acute pancreatitis model in rats the enormous rise in plasma amylase and lipase induced by caerulein. With a 10fold lower dose, only Devazepide and 15a showed a significant antagonism on the rise of both enzyme activities (Table 3). Since the affinity of 2a and 15a at CCK1 receptors was approximately identical, it is supposed that the bioavailability of 15a is higher. Such contention is supported by the results obtained in this pancreatitis model after oral administration of test compounds. As can be seen in Table 4, only Devazepide was effective at the lower dose of 0.1 mg/kg po while 15a, but not 2a, significantly prevented the rise in enzyme activity at the dose of 1 mg/kg po. Spontaneous locomotor activity of mice was significantly reduced by CCK-8, 10 µg/kg, by approximately 60% (Figure 2). All of the tested compounds were able to significantly reverse the hypomotility when given ip at the dose of 0.1 mg/kg (not shown). The time course of the antagonism to CCK-8 was studied after oral administration of a 10-fold higher dose, 1 mg/kg, which did not produce on its own any significant effect on the locomotion. While the antagonism to the hypomotility was significant with all four compounds given 1 or 2 h before CCK-8, only Devazepide significantly antagonized the hypomotility when given 4 h before CCK (Figure 2). Nevertheless, at this time point the distance travelled by mice receiving CCK-8 or the combined treatment CCK-8 + 2a was almost identical (Figure 2A),

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Figure 2. Effect of the CCK1 antagonists devazepide (1) and 2a (A), 14a and 15a (B) on the hypomotility induced by CCK-8 in mice. Antagonists (1 mg/kg po) were given at the times indicated before CCK-8 (10 µg/kg). Spontaneous locomotor activity (mean ( SEM of 8-12 animals) was measured 5 min after CCK-8 for 30 min *p < 0.05 **p < 0.01 vs control; +p < 0.05, ++p < 0.01 vs CCK-8 (ANOVA followed by Scheffe´’s test).

whereas a certain trend toward an antagonism of the CCK-8 effect by either compound 14a or 15a was observed in Figure 2B, suggesting a slightly higher oral bioavailability in mice of compounds 14a and 15a as compared to compound 2a. In conclusion, the results herein described show the strong structural requirements at the tryptophan domain for CCK1 receptor binding of this new family of highly selective CCK1 antagonists based on the structure of 5-(tryptophyl)amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine. Thus, both the indol of the Trp side chain and its orientation are important structural features, and the presence of the H-bonding acceptor carbonyl group of the carboxamide bond and the Boc group or some surrogate, such as the 3,3-dimethylbutyryl or the tert-butylaminocarbonyl, is essential. Compounds 14a and 15a, which incorporate these surrogates, with much higher chemical stability in acid media than the lead compound 2a, showed similar CCK receptor in vitro activity to that of this prototype. These changes enhanced or tended to enhance their oral bioavailability. This improvement in the in vivo CCK1 receptor antagonism profile was particularly significant in the case of the tert-butylaminocarbonyl derivative 15a. Experimental Section Chemistry. All reagents were of commercial quality. Solvents were dried and purified by standard methods. Amino acid derivatives were obtained from Bachem Feinchemikalien AG. Analytical TLC was performed on aluminum sheets coated

Bartolome´ -Nebreda et al. with a 0.2 mm layer of silica gel 60 F254, Merck. Silica gel 60 (230-400 mesh), Merck, was used for flash chromatography. Melting points were taken on a micro hot stage apparatus and are uncorrected. 1H NMR spectra were recorded with a Varian Gemini-200,Varian XL-300, or Unity-500 spectrometer, operating at 200, 300, or 500 MHz, using TMS as reference. 13C NMR spectra were recorded with the Varian Gemini-200 spectrometer, operating at 50 MHz. Elemental analyses were obtained on a CH-O-RAPID apparatus. Analytical HPLC was performed on a Waters Nova-pak C18 (3.9 × 150 mm, 4 µm) column, with a flow rate of 1 mL/min, and using a tunable UV detector set at 214 nm. Mixtures of CH3CN (solvent A) and 0.05% TFA in H2O (solvent B) were used as mobile phase. General Procedure for the Synthesis of the 1,3-Dioxoperhydropyrido[1,2-c]pyrimidine Derivatives 7-12. TFA (0.5 mL) was added to a solution of (4aR*,5S*)-2-benzyl-5[(tert-butoxycarbonyl)amino]-1,3-dioxoperhydropyrido[1,2-c]pyrimidine [6a,b, obtained as a (1:4) racemic mixture of 6a and 6b, from Boc-L-Orn(Z)-OH for 7a,b and 8a,b, and as a (4:1) mixture from Boc-D-Orn(Z)-OH for 9-12] (75 mg, 0.2 mmol) in CH2Cl2 (1 mL); after 1 h at room temperature, the solvents were evaporated to dryness. The residue was dissolved in dry CH2Cl2 (5 mL), and the corresponding acid (indol-3-yl-acetic acid, indol-2-yl-carboxylic acid, Boc-L-Phe-OH, Boc-R-Me-L-TrpOH, Boc-R-Me-D-Trp-OH, or 2-Boc-tetrahydro-β-carbolin-3-ylcarboxylic acid) (0.22 mmol), (benzotriazolyloxy)-tris(dimethylamino)phosphonium hexafluorophosphate (BOP; 97 mg, 0.22 mmol), and triethylamine (63 µL, 0.45 mmol) were added successively to that solution; stirring was continued at room temperature for 12 h. Afterward, the reaction mixture was diluted with CH2Cl2 (20 mL), and the resulting solution was washed successively with 10% citric acid (2 × 10 mL), saturated NaHCO3 (2 × 10 mL), H2O (2 × 10 mL), and brine (10 mL), dried over Na2SO4, and evaporated. Flash chromatography of the residue with 20-50% gradients of EtOAc in hexane yielded in each case: the (1:4) racemic mixtures 7ab (68%) and 8ab (71%), the (6:1) diastereoisomeric mixtures 10ab (90%) and 11ab (94%), which could not be resolved, and the (4:1) diasteroisomeric mixtures 9ab and 12ab. Preparative TLC of 9ab with (9:1) hexane-EtOAc yielded isolated 9a (85%), while 12ab was resolved by preparative TLC with (9:1) ethyl ether-EtOAc into 12a (49%) and 12b (7%). The most significant analytical and spectroscopic data of these compounds are summarized in Table 5. Synthesis of (4aS,5R)- and (4aR,5S)-2-Benzyl-5-(L-tryptophyl)amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine Trifluoroacetate (13a and 13b). TFA (0.5 mL) was added to a solution of (4aS,5R)- or (4aR,5S)-2-benzyl-5-(BocL -tryptophyl)amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine (2a or 2b) (112 mg, 0.2 mmol) in CH2Cl2 (1 mL); after 1 h at room temperature, the solvents were evaporated to dryness. Flash chromatography of the residue with 1-5% gradient of MeOH in CH2Cl2 yielded the corresponding N deprotected tryptophyl derivative 13a or 13b, respectively, whose significant analytical and spectroscopic data are summarized in Table 6. General Procedure for the Replacement of the N-Boc Protecting Group of 2a and 2b. Synthesis of Compounds 14a-17b. TFA (0.5 mL) was added to a solution of (4aS,5R)or (4aR,5S)-2-benzyl-5-(Boc-L-tryptophyl)amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine (2a or 2b) (112 mg, 0.2 mmol) in CH2Cl2 (1 mL); after 1 h at room temperature, the solvents were evaporated to dryness. The residue was dissolved in dry THF (1 mL), and triethylamine (56 µL, 0.4 mmol) was added to that solution, which was stirred for 10 min. Then, the corresponding acylating agent (3,3-dimethylbutyryl chloride, tert-butyl isocyanate, 1-adamantylcarbonyl chloride, or 2-adamantyl chloroformate) was added (0.25 mmol), stirring was continued at room temperature for 1.5 h, and the reaction mixture was evaporated to dryness. The resulting residue was purified by preparative TLC with (1:2) EtOAc-ethyl ether in the tryptophyl derivatives 14a and 15a, and by flash chromatography in the case of 16b and 17b, using a (33-50%)



Table 5. Significant Analytical and Spectroscopic Data of Compounds 7-12

7ab

8ab

9a

10ab

11ab

12a

12b

In-2-yl-CO (4aR*,5S*) C24H24N4O3 71 210-212 13.16 (45:55)

In-3-yl-CH2-CO (4aR*,5S*) C25H26N4O3 68 91-92 9.36 (45:55)

Boc-L-Phe (4aS,5R) C29H36N4O5 85 168-170 46.54 (33:67)

Boc-R-Me-L-Trp (4aR*,5S*) C32H39N5O5 90

Boc-R-Me-D-Trp (4aR*,5S*) C32H39N5O5 94

42.00 (33:67)

46.27 (33:67)

2-Boc-THBC-3-yl-COa (4aS,5R) C32H37N5O5 49 128-130 37.93 (37:63)

2-Boc-THBC-3-yl-COa (4aR,5S) C32H37N5O5 7 139-141 36.13 (37:63)

4.93 2.76, 2.91

3.64 4.80, 4.90 2.61

4.15 4.92, 4.98 2.56, 2.72

1.53, 1.55 4.96 2.54, 2.76

5.16f 4.88, 4.96 2.34

5.20f 4.92 2.39, 2.49

4a-H 5-H 5-NH 6-H

3.22 3.94 5.88 1.20, 2.09

2.70 3.64 5.47 1.00, 1.81

2.92 3.61 5.59 1.08, 1.66

3.07 3.64 5.83 1.30, 1.94

3.00 3.62 5.76 1.40, 1.88

7-H 8-H

1.45-1.90 2.65, 4.34

1.40-1.65 2.38, 4.18

1.50 2.51, 4.18

2.89, 2.96 3.71 6.18, 6.35 1.25, 1.88 1.25, 1.73 1.59, 1.73 2.60, 4.33 2.60, 4.31

1.52, 1.54 5.02 2.57, 2.69 2.57, 2.54 2.87, 2.95 3.69 6.16, 6.35 1.18, 1.81 1.25, 1.87 1.44-1.59 2.56, 4.30 2.56, 4.33

1.56, 1.76 2.61, 4.32

1.56, 1.73 2.60, 4.32

R stereochemistry formulab yield (%) mp (°C) tR (A:B)c 1H NMRd R (R)e 2-CH2 4-H

a THBC ) tetrahydro-β-carboline. b Satisfactory analyses for C, H, N. c A ) CH CN; B ) 0.05% TFA in H O. d In CDCl , measured at 3 2 3 300 MHz. e H, except for 10ab and 11ab where it is CH3. f J3,4 in the tetrahydro-β-carboline skeleton 0 and 6 Hz.


13a R1 stereochemistry formulaa yield (%) mp (°C) tR (A:B)c 1H NMRd R-H (Trp) NH-R1 2-CH2 4-H 4a-H 5-H 5-NH 6-H 7-H 8-H

13b

14a tBut-CH

15a

16b

17b

tBut-NH-CO

H (4aS,5R) C28H30F3N5O5b 89 foam 5.33 (33:67)

H (4aR,5S) C28H30F3N5O5b 92 foam 14.34 (30:70)

2-CO (4aS,5R) C32H39N5O4 80 138-140 35.13 (40:60)

(4aS,5R) C31H38N6O4 86 132-134 57.67 (33:67)

1-Adc (4aR,5S) C37H43N5O4 83 117-119 31.20 (33:67)

2-Adoc (4aR,5S) C37H43N5O5 59 137-139 23.67 (33:67)

4.29

4.19

4.82, 4.93 2.75, 2.90 3.27 3.52 8.27 1.20 1.56 2.62, 4.12

4.87, 4.97 2.64, 2.78 3.42 3.76 7.32 1.48-1.89 1.48-1.89 2.71, 4.25

4.66 5.99 4.89, 4.98 2.51, 2.69 2.86 3.54 5.98 0.97, 1.59 1.43 2.50, 4.26

4.53 5.51 4.84, 4.96 2.52, 2.64 2.70 3.57 5.51 0.98, 1.50 1.50 2.46, 4.21

4.71 5.74 4.91, 4.97 2.23 2.51 3.57 5.74 1.14, 1.87 1.48-1.84 2.50, 4.24

4.48 5.32 4.91, 4.98 2.16 2.54 3.59 5.38 1.17, 1.89 1.41-1.84 2.49, 4.24

a Satisfactory analyses for C, H, N. b As trifluoroacetate salt. c A ) CH CN; B ) 0.05% TFA in H O. 3 2 except for 13a and 13b which were registered in (CD3)2CO.

gradient of EtOAc in hexane as eluant. Significant analytical and spectroscopic data of these compounds are summarized in Table 6. Synthesis of (4aS,5R)-2-Benzyl-5-[(2S)-2-N-(tert-butoxycarbonyl)amino-3-(indol-3-yl)-propyl]amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine (18a). TFA (0.5 mL) was added to a solution of (4aR*,5S*)-2-benzyl-5-[(tert-butoxycarbonyl)amino]-1,3-dioxoperhydropyrido[1,2-c]pyrimidine [6a,b, obtained as a (9:1)20 racemic mixture of 6a and 6b] (75 mg, 0.2 mmol) in CH2Cl2 (1 mL); after 1 h at room temperature, the solvents were evaporated to dryness. The residue was dissolved in MeOH (1.5 mL), and 4 Å molecular sieves and triethylamine (28 µL, 0.2 mmol) were added; after 15 min of stirring, Boc-L-tryptophanal (58 mg, 0.2 mmol), ZnCl2 (14 mg,

d

Measured at 300 MHz in CDCl3,

0.1 mmol), and NaBH3CN (16 mg, 0.21 mmol) were added successively, and stirring at room temperature was continued for 15 h. Afterward, the reaction mixture was filtered and evaporated to dryness. The residue was dissolved in EtOAc (50 mL), and the resulting solution was washed successively with 0.1 N HCl (2 × 25 mL), saturated NaHCO3 (2 × 25 mL), H2O (2 × 25 mL), and brine (25 mL), dried over Na2SO4, and evaporated. Flash chromatography of the residue with 4% of EtOAc in ethyl ether allowed the isolation of the major diastereoisomer 18a, whose significant analytical and spectroscopic data are shown in Table 7. Synthesis of the Cyanomethyleneamino Carboxamide Surrogate Containing Compounds 19-22. TFA (1 mL) was added to a solution of (4aR*,5S*)-2-benzyl-5-[(tert-butoxycar-

4666




R1 X stereochemistry formulaa yield (%) mp (°C) tR (A:B)b 1H NMRc 1′-Η 2′-H NH-R1 2-CH2 4-H 4a-H 5-H 5-NH 6-H 7-H 8-H 13CNMRd C1′ CN

18a

19a

19b

20a

21a

21b

22a

Boc CH2 (4aS,5R) C31H39N5O4 62 80-82 31.27 (40:60)

Boc [(R)CHCN] (4aS,5R) C32H38N6O4 31 99-101 17.40 (45:55)

Boc [CHCN] (4aR,5S) C32H38N6O4 9 102-104 16.53 (45:55)

Boc [(S)CHCN] (4aS,5R) C32H38N6O4 21 106-108 20.13 (45:55)

Z [(R)CHCN] (4aS,5R) C35H36N6O4 34 68-70 20.13 (45:55)

Z [CHCN] (4aR,5S) C35H36N6O4 10 foam 20.33 (45:55)

Z [(S)CHCN] (4aS,5R) C35H36N6O4 17 67-69 20.20 (45:55)

2.46, 2.98 3.96 4.60 4.96 2.70, 3.02 2.98 2.15 2.17 1.10, 2.15 1.72, 1.47 2.63, 4.31

3.57 4.22 4.74 4.95 2.60, 2.93 2.86 2.23 1.69 1.12, 2.40 1.44, 1.70 2.53, 4.26

3.64 4.26 4.80 4.95 2.47, 2.87 2.87 2.21 1.71 1.06, 2.21 1.39, 1.73 2.53, 4.27

3.79 4.27 4.86 4.96, 4.90 2.50, 2.92 2.93 2.40 1.72 1.12, 1.95 1.44, 1.69 2.60, 4.30

3.49 4.17 5.07 4.87 2.43, 2.76 2.61 2.09 1.69 1.03, 2.27 1.38, 1.65 2.28, 4.21

3.64 4.28 5.03 4.93 2.33, 2.80 2.80 2.24 1.62 1.16, 2.24 1.25-1.76 2.56, 4.28

3.81 4.34 5.20 4.97, 4.90 2.45, 2.84 2.84 2.37 1.68 0.98, 1.93 1.36, 1.66 2.54, 4.27

50.60

53.17 120.10

53.94 118.48

52.93 117.77

54.34 120.18

54.75 118.53

53.94 117.82

a Satisfactory analyses for C, H, N. b A ) CH CN; B ) 0.05% TFA in H O. c In CDCl , registered at 300 MHz. 3 2 3 at 50 MHz.

bonyl)amino]-1,3-dioxoperhydropyrido[1,2-c]pyrimidine [6a,b, obtained as a (9:1)20 racemic mixture of 6a and 6b] (160 mg, 0.43 mmol) in CH2Cl2 (2 mL); after 1 h at room temperature, the solvents were evaporated to dryness. The residue was dissolved in MeOH (3 mL), to this solution triethylamine (67 µL, 0.47 mmol) was added, and after 15 min of stirring, the reaction mixture was cooled at -20 °C. Boc- or Z-L-tryptophanal (1.29 mmol), ZnCl2 (59 mg, 0.43 mmol), and TMSCN (0.161 µL, 1.29 mmol) were added successively, and stirring was continued, first at -20 °C for 1 h and then at 0 °C for 15 h. Afterward, the reaction mixture was evaporated to dryness. The residue was dissolved in EtOAc (50 mL), and the resulting solution was washed successively with H2O (2 × 25 mL) and brine (25 mL), dried over Na2SO4, and evaporated. Preparative TLC of the residue using 1% of MeOH in CH2Cl2 yielded in each case, in decreasing order of Rf, the Boc protected compounds 19a, 19b, and 20a, and the Z protected analogues 21a, 21b, and 22a, whose significant analytical and spectroscopic data are summarized in Table 7. Synthesis of (4aS,5R)-2-Benzyl-5-[(4S,5R)-5-cyano-4(indol-3-yl)methyl-2-oxoimidazolidin-1-yl]-1,3-dioxoperhydropyrido[1,2-c]pyrimidine (25a). A solution of (4aS,5R)2-benzyl-5-[(1R,2S)-2-N-(benzyloxycarbonyl)amino-1-cyano3-(indol-3-yl)-propyl]amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine (21a) (60 mg, 0.1 mmol) in 10-5 N HCl in MeOH (20 mL) was hydrogenated at room temperature and 40 psi of pressure for 4 days, in the presence of 10% Pd(C) (28 mg). After filtering off the catalyst, the solvent was evaporated, and the resulting residue was dissolved in dry CH2Cl2 (6 mL). Triethylamine (28 µL, 0.2 mmol) was added to the resulting solution, and the mixture was stirred at room temperature for 15 min. Then, bis(trichloromethyl)carbonate (6 mg, 0.05 mmol) and triethylamine (17 µL, 0.12 mmol) were added at 0 °C, and the stirring was continued at this temperature for 12 h. Afterward, the reaction mixture was diluted with CH2Cl2 (25 mL), washed with water (10 mL) and brine (10 mL), and dried over Na2SO4. Removal of the solvent and preparative TLC of the residue, using 6% of MeOH in CH2Cl2 as eluant, gave the 2-oxoimidazolidine derivative 25a as a foam (13 mg, 26%): RP

d

In CDCl3, measured

HPLC tR ) 5.73 (A:B ) 40:60); 1H NMR (300 MHz, CDCl3) δ 1.54 (m, 1H, 7-H), 1.80 (m, 3H, 6-H and 7-H), 2.63 (m, 1H, 4-H), 2.67 (m, 1H, 8-H), 2.94 (dd, 1H, 4-H, J ) 6 and 17 Hz), 3.34 and 3.36 [2dd, 2H, 4-CH2 (2-oxoimidazolidine), J ) 6 and 15 Hz], 3.37 (m, 1H, 5-H), 3.79 (m, 1H, 4a-H), 4.16 [d, 1H, 5-H (2-oxoimidazolidine), J ) 5 Hz], 4.25 [m, 1H, 4-H (2oxoimidazolidine)], 4.35 (m, 1H, 8-H), 4.94 and 5.00 (2d, 2H, 2-CH2, J ) 14 Hz), 7.13-7.54 (m, 10H, aromatics), 8.27 [s, 1H, 1-H (In)]; 13C NMR (125 MHz, CDCl3) δ 23.77 (C7), 27.10 (C6), 30.75 [4-CH2 (2-oxoimidazolidine)], 33.59 (C4), 44.14 (2CH2), 44.96 (C8), 49.14 [C5 (2-oxoimidazolidine)], 52.72 (C4a), 55.47 [C5, and C4 (2-oxoimidazolidine)], 108.41 [C3 (In)], 111.75 [C7 (In)], 117.28 (CN), 117.95 [C4 (In)], 120.39 [C5 (In)], 122.91 [C4 (Ph)], 123.18 [C2 (In)], 126.97 [C3a (In)], 127.36 [C6 (In)], 128.40 and 128.46 [C2 and C3 (Ph)], 136.33 [C7a (In)], 137.59 [C1 (Ph)], 153.53 (C1), 158.19 [C1 (2-oxoimidazolidine)], 167.38 (C3). Anal. (C28H28N6O3) C, H, N. Binding Assays. CCK1 and CCK2 receptor binding assays were performed using rat pancreas and cerebral cortex homogenates respectively, according to the method described by Dauge´ et al,36 with minor modifications. Briefly, rat pancreas tissue was carefully cleaned and homogenized in Pipes HCl buffer, pH 6.5, containing 30 mM MgCl2 (15 mL/g of wet tissue), and the homogenate was then centrifuged twice at 4 °C for 10 min at 50000g. For displacement assays, pancreatic membranes (0.2 mg protein/tube) were incubated with 0.5 nM [3H]pCCK-8 in Pipes HCl buffer, pH 6.5, containing MgCl2 (30 mM), bacitracin (0.2 mg/mL), and soybean trypsin inhibitor (SBTI, 0.2 mg/mL), for 120 min at 25 °C. Rat brain cortex was homogenized in 50 mM Tris-HCl buffer pH 7.4 containing 5 mM MgCl2 (20 mL/g of wet tissue), and the homogenate was centrifuged twice at 4 °C for 35 min at 100000g. Brain membranes (0.45 mg protein/tube) were incubated with 1 nM [3H]pCCK-8 in 50 mM Tris-HCl buffer, pH 7.4, containing MgCl2 (5 mM) and bacitracin (0.2 mg/mL) for 60 min at 25 °C. Final incubation volume was 0.5 mL in both cases. Nonspecific binding was determined using 1 µM CCK-8 as the cold displacer. The inhibition constants (Ki) were calculated

Selective CCK1 Receptor Antagonists using the equation of Cheng and Prusoff from the displacement curves analyzed with the receptor fit competition LUNDON program. Caerulein-Induced Acute Pancreatitis in Rats. Acute pancreatitis was induced in male Wistar rats (190-210 g) deprived of food for 24 h by four subcutaneous injections of caerulein (10 µg/kg) at hourly intervals as described.41 CCK antagonists were administered by intraperitoneal or oral route (0.25 mL/100 g) 30 or 60 min, respectively, before the first caerulein injection. Three hours after the last caerulein injection, blood was collected and the pancreas was removed. Amylase and lipase activities in plasma were measured by means of commercially available kits (Boehringer Mannheim). Spontaneous Locomotor Activity. Hypomotility was induced in mice by ip injection of CCK-8 (10 µg/kg) 5 min before recording the locomotion for 30 min.40 Test compounds (0.1 mL/10 g) were given ip 30 min before CCK or po at different times before CCK. Locomotion was measured by placing the mice in a black wooden open-topped box (65 × 65 × 45 cm3) and recording the distance travelled in centimeters by using a digital Videomex-V-system (Columbus Inst.) working with the appropriate computer program.

Acknowledgment. This work has been supported by the CICYT (SAF 97-0030) and Fundacioń La Caixa (97/022). The contribution of Jose´ M. Bartolome´-Nebreda to this work was awarded with the 1997 JanssenCilag award of the Spanish Society of Therapeutic Chemistry for Young Researchers.


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References (1) Crawley, N. J.; Corwin, R. L. Biological Actions of Cholecystokinin. Peptides 1994, 15, 731-755. (2) Wank, S. A. Cholecystokinin Receptors. Am. J. Physiol. 1995, 269, G628-G646. (3) Crawley, N. J. Cholecystokinin-Dopamine Interactions. Trends Pharmacol. Sci. 1991, 12, 232-236. (4) Baber, N. S.; Dourish, C. T.; Hill, D. R. The Role of CCK, Caerulein and CCK Antagonists in Nociception. Pain 1989, 39, 307-328. (5) Dourish, C. T.; Ruckert, A. C.; Tattersall, F. D.; Iversen, S. D. Evidence that Decreased Feeding Induced by Systemic Injection of Cholecystokinin is Mediated by CCK-A Receptors. Eur. J. Pharmacol. 1989, 173, 233-234. (6) Ravard, S.; Dourish, C. T. Cholecystokinin and Anxiety. Trends Pharmacol. Sci. 1990, 11, 271-273. (7) Harro, J.; Vasar, E.; Bradwejn, J. CCK in Animal and Human Research on Anxiety. Trends Pharmacol. Sci. 1993, 14, 244249. (8) Singh, L.; Lewis, A. S.; Field, M. J.; Hughes, J.; Woodruff, G. N. Evidence for an Involvement of the Brain Cholecystokinin B Receptor in Anxiety. Proc. Natl. Acad. Sci. U.S.A. 1991, 88, 1130-1133. (9) Derrien, M.; McCort-Tranchepain, I.; Ducos, B.; Roques, B. P.; Durieux, C. Hetereogeneity of CCK-B Receptors Involved in Animal Models of Anxiety. Pharmacol. Biochem. Behav. 1994, 49, 133-141. (10) Itoh, S.; Lal, H. Influences of Cholecystokinin and Analogues on Memory Process. Drug Dev. Res. 1990, 21, 257-276. (11) Wang, R. Y. Cholecystokinin, Dopamine, and Schizophrenia: Recent Progress and Current Problems. Ann. N.Y. Acad. Sci. 1988, 537, 362-379. (12) Schalling, M.; Friberg, K.; Serrogy, K.; Riederer, P.; Schiffman, S. N.; Mailleux, P.; Vanderhaeghen, J. J.; Kuga, S.; Goldstein, M.; Kitahama, K.; Luppi, P. H.; Jouvet, M.; Ho¨kfelt, T. Analysis of Expression of Cholecystokinin in the Ventral Mesencephalon of Several Species and in Human Schizophrenia. Proc. Natl. Acad. Sci. U.S.A. 1990, 87, 8427-8431. (13) For reviews, see for example: (a) Dunlop, J. CCK Receptor Antagonists. Gen. Pharmacol. 1998, 31, 519-524. (b) Shlik, J.; Vasar, E.; Bradwejn, J. Cholecystokinin and Psychiatric Disorders. Role in Aetiology and Potential of Receptor Antagonists in Therapy. CNS Drugs 1997, 8, 134-152. (14) (a) Dauge´, V.; Steimes, P.; Derrien, M.; Beau, N.; Roques, B. P.; Fe´ger, J. CCK8 Effects on Motivational and Emotional States of Rats Involve CCK-A Receptors of the Postrero-median Part of the Nucleus Accumbens. Pharmacol. Biochem. Behav. 1987, 34, 157-163. (b) Hendrie, C. A.; Dourish, C. T. Anxiolytic Profile of the Cholecystokinin Antagonist Devazepide in Mice. Br. J.

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(32)

(33)

Pharmacol. 1990, 99, 138P. (c) Hendrie, C. A.; Neill, J. C.; Shepherd, J. K.; Dourish, C. T. The Effects of CCK-A and CCK-B Antagonists on Activity in the Black/White Exploration Model of Anxiety in Mice. Physiol. Behav. 1993, 54, 689-693. Dourish, C. T.; Hawley, D.; Iversen, S. D. Enhancement of Morphine Analgesia and Prevention of Morphine Tolerance in the Rat by the Cholecystokinin Antagonist L-364,718. Eur. J. Pharmacol. 1988, 147, 469-472. Woodruff, G. N.; Hill, D. R.; Boden, P.; Pinnock, R.; Singh, L.; Hughes, J. Functional Role of Brain CCK Receptors. Neuropeptides 1991, 19 (Suppl.), 45-46. Hughes, J.; Boden, P.; Costall, B.; Domeney, A.; Kelly, E.; Horwell, D. C.; Hunter, J. C.; Pinnock, R. D.; Woodruff, G. N. Development of a Class of Selective Cholecystokinin Type B Receptor Antagonist Having Anxiolytic Activity. Proc. Natl. Acad. Sci. U.S.A. 1990, 87, 6728-6732. Chang, R. S. L.; Lotti, V. J. Biochemical and Pharmacological Characterization of a New and Extremely Potent and Selective Nonpeptide Cholecystokinin Antagonist. Proc. Natl. Acad. Sci. U.S.A. 1986, 83, 4923-4926. Woodruff, G. N.; Hughes, J. Cholecystokinin Antagonists. Annu. Rev. Pharmacol. Toxicol. 1991, 31, 469-501. Martıń-Martıńez, M.; Bartolome´-Nebreda, J. M.; Go´mez-Monterrey, I.; Gonza´lez-Mun˜iz, R.; Garcıá-Lo´pez, M. T.; Ballaz, S.; Barber, A.; Fortunõ, A.; Del Rıó, J.; Herranz, R. Synthesis and Stereochemical Structure-Activity Relationships of 1,3-dioxoperhydropyrido[1,2-c]pyrimidine Derivatives: Potent and Selective Cholecystokinin-A Receptor Antagonists. J. Med. Chem. 1997, 40, 3402-3407. Ballaz, S.; Barber, A.; Fortunõ, A.; Del Rıó, J.; Martıń-Martıńez, M.; Go´mez-Monterrey, I.; Herranz, R.; Gonza´lez-Mun˜iz, R.; Garcıá-Lo´pez, M. T. Pharmacological Evaluation of IQM-95,333, a Highly Selective CCKA Receptor Antagonist with Anxiolyticlike Activity in Animal Models. Br. J. Pharmacol. 1997, 121, 759-767. Bock, G. M.; DiPardo, R. M.; Evans, B. E.; Rittle, K. E.; Whitter, W. L.; Veber, D. F.; Anderson, P. S.; Freidinger, R. M. Benzodiazepine Gastrin and Brain Cholecystokinin Receptor Ligands: L-365,260. J. Med. Chem. 1989, 32, 13-16. Evans, B. E.; Rittle, K. E.; Bock, M. G.; DiPardo, R. M.; Freidinger, R. M.; Whitter, W. L.; Lundell, G. F.; Veber, D. F.; Anderson, P. S.; Chang, R. S. L.; Lotti, V. J.; Cerino, D. J.; Chen, T. B.; Kling, P. J.; Kunkel, K. A.; Springer, J. P.; Hirshfield, J. Methods for Drug Discovery: Development of Potent, Selective, Orally Effective Cholecystokinin Antagonists. J. Med. Chem. 1988, 31, 2235-2246. Bystrov, V. F. Spin-Spin Coupling and the Conformational States of Peptide Systems. Prog. Nucl. Magn. Reson. Sp. 1976, 10, 41-81. Kessler, H.; Griesinger, C.; Wagner, K. Peptide Conformations. 42.1,2 Conformation of Side Chains Peptides Using Heteronuclear Coupling Constants Obtained by Two-Dimensional NMR Spectroscopy. J. Am. Chem. Soc. 1987, 109, 6927-6933. Cannon, J. B.; Adjei, L. A.; Fu Lu, M. Y.; Garran, K. Alternate Drug Delivery Routes for A-71623, a Potent Cholecystokinin-A Receptor Agonist Tetrapeptide. J. Drug Targeting 1996, 4, 6978. Higginbottom, M.; Kneen, C.; Ratcliffe, G. S. Rationally Designed “Dipeptoid” Analogues of CCK. A Free-Wilson/Fujita-Ban Analysis of Some R-Methyltryptophan Derivatives as CCK-B Antagonists. J. Med. Chem. 1992, 35, 1572-1577. Spatola, A. F. Peptide Backbone Modifications: A StructureActivity Analysis of Peptides Containing Amide Bond Surrogates. Conformational Constraints. In Chemistry and Biochemistry of Amino Acids, Peptides and Proteins; Weinstein, B., Ed.; Marcel Dekker: Nueva York, 1983; Vol. 7, pp 267-357. Bladon, C. M. Analogue and Conformational Studies on Peptide Hormones and other Biologically Active Peptides. Amino Acids, Pept. Proteins 1995, 26, 157-235. Biagini, S. C. G.; North, M. Analogue and Conformational Studies on Peptide Hormones and other Biologically Active Peptides. Amino Acids, Pept. Proteins 1996, 27, 156-230. Herranz, R.; Sua´rez-Gea, M. L.; Vinuesa, S.; Garcıá-Lo´pez, M. T.; Martıńez, A. Synthesis of Ψ[CH(CN)NH]Pseudopeptides. A New Peptide Bond Surrogate. Tetrahedron Lett. 1991, 32, 75797582. Gonza´lez-Mun˜iz, R.; Garcıá-Lo´pez, M. T.; Go´mez-Monterrey, I.; Herranz, R.; Jimeno, M. L.; Sua´rez-Gea, M. L.; Johansen, N. L.; Madsen; K.; Thøgersen, H.; Suzdak, P. Ketomethylene and (Cyanomethylene)amino Pseudopeptide Analogues of the C-Terminal Hexapeptide of Neurotensin. J. Med. Chem. 1995, 38, 1015-1021. Herrero, S.; Sua´rez-Gea, M. L.; Gonza´lez-Mun˜iz, R.; GarcıáLo´pez, M. T.; Herranz, R.; Ballaz, S.; Barber, A.; Fortunõ, A.; Del Rıó, J. Pseudopeptide CCK-4 Analogues Incorporating the Ψ[CH(CN)NH] Peptide Bond Surrogate. Bioorg. Med. Chem. Lett. 1997, 7, 855-860.

4668


(34) Herranz, R.; Sua´rez-Gea, M. L.; Vinuesa, S.; Garcıá-Lo´pez, M. T.; Studies on the Synthesis of Cyanomethyleneamino Pseudopeptides. J. Org. Chem. 1993, 58, 5186-5191. (35) Barany, G.; Merrifield, R. B.; Solid-Phase Peptide Synthesis. In The Peptides. Analysis, Synthesis, Biology; Gross, E., Meienhofer, J., Eds.; Academic Press: New York, 1980; Vol. 2, pp 1-284. (36) Dauge´, V.; Bohme, G. A.; Crawley, J. N.; Duriex, C.; Stutzman, J. M.; Feger, J.; Blanchard, J. C.; Roques, B. P. Investigation of Behavioural and Electrophysiological Responses Induced by Selective Stimulation of CCKB Receptors by Using a New Highly Potent CCK Analog: BC 264. Synapse 1990, 6, 73-80. (37) Horwell, D. C.; Birchmore, B.; Boden, P. R.; Higginbottom, M.; Ping Ho, Y.; Hughes, J.; Hunter, J. C.; Richardson, R. S. R-Methyl Tryptophanylphenylalanines and their Arylethylamine “Dipeptoid” Analogues of the Tetrapeptide Cholecystokinin (3033). Eur. J. Med. Chem. 1990, 25, 53-60. (38) Boden, P. R.; Higginbottom, M.; Hill, D. R.; Horwell, D. C.; Hughes, J.; Rees, D. C.; Roberts, E.; Singh, L.; Suman-Chauhan,

Bartolome´ -Nebreda et al. N.; Woodruff, G. N. Cholecystokinin Dipeptoid Antagonists: Design, Synthesis, and Anxiolytic Profile of Some Novel CCK-A and CCK-B Selective and “Mixed” CCK-A/CCK-B Antagonists. J. Med. Chem. 1993, 36, 552-565. (39) Wettstein, J. G.; Bueno, L.; Junien, J. L. CCK Antagonists: Pharmacological and Therapeutic Interest. Pharmacol. Ther. 1994, 62, 267-284. (40) O’Neill, M. F.; Dourish, C. T.; Iversen, S. D. Hypolocomotion Induced by Peripheral or Central Injection of CCK in the Mouse is Blocked by the CCKA Receptor Antagonist Devazepide but not by the CCKB Receptor Antagonist L-365,260. Eur. J. Pharmacol. 1991, 193, 203-208. (41) Tani, S.; Otsuki, M.; Itoh, H.; Fujii, M.; Nakamura, T.; Oka, T.; Baba, S. Histologic and Biochemical Alterations in Experimental Acute Pancreatitis Induced by Supramaximal Caerulein Stimulation. Int. J. Pancreatol. 1987, 2, 337-348.

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